scholarly journals Effect of Shape and Size on Curie Temperature, Debye Frequency, Melting Entropy and Enthalpy of Nanosolids

2018 ◽  
Vol 34 (5) ◽  
pp. 2282-2291
Author(s):  
Madan Singh ◽  
Benedict Molibeli Taele ◽  
Ghanshyam Patel
Keyword(s):  
Curie Temperature ◽  
Metallic Nanoparticles ◽  
Theory Model ◽  
Model Free ◽  
Bond Theory ◽  
Melting Thermodynamics ◽  
Debye Frequency ◽  
Shape And Size ◽  
Temperature Melting ◽  
Melting Entropy

The shape and size dependent melting thermodynamics of metallic nanoparticles are predicted by application of bond theory model, free of any adjustable parameter. Thermodynamic properties like Debye frequency, Curie temperature, melting entropy and enthalpy of Al, Sn, In, Cu, β-Fe and Fe3O4 for spherical and non spherical shapes nanoparticles with different size have been studied. In this model, the effects of relaxation factor for the low dimension solids are considered. The depression in Debye frequency, Curie temperature, melting entropy and enthalpy is predicted. The model predictions are supported by the available experimental and simulation results.

Modeling the melting temperature, melting entropy and melting enthalpy of freestanding metallic nanoparticles

2020 ◽  
Vol 241 ◽  
pp. 122280 ◽  
Author(s):  
Xiao Bao Jiang ◽  
Bei Bei Xiao ◽  
Rui Lan ◽  
Xiao Yan Gu ◽  
Hong Chao Sheng ◽  
...  
Keyword(s):  
Melting Temperature ◽  
Metallic Nanoparticles ◽  
Melting Enthalpy ◽  
Temperature Melting ◽  
Melting Entropy

Diameter-dependent thermodynamic and elastic properties of metallic nanoparticles

2015 ◽  
Vol 29 (08) ◽  
pp. 1550025 ◽  
Author(s):  
Jeewan Chandra ◽  
Kuldeep Kholiya
Keyword(s):  
Elastic Properties ◽  
Metallic Nanoparticles ◽  
Close Agreement ◽  
Present Formulation ◽  
Evaporation Temperature ◽  
Theoretical Approaches ◽  
Simple Theoretical Model ◽  
Experimental Findings ◽  
Temperature Melting ◽  
Melting Entropy

A simple theoretical model has been proposed to study the diameter-dependent properties of metallic nanoparticles, i.e. Ag , Au , Al , Ni , Pb , Cu and Fe . The diameter-dependent thermodynamic properties includes melting temperature, Debye temperature, evaporation temperature, melting enthapy and melting entropy. The model is also extended to study the diameter-dependent elastic properties including bulk modulus, Young's modulus and thermal expansion coefficient. On comparison with available experimental findings and other theoretical approaches, the results obtained with the present formulation depict a close agreement and demonstrate the validity of the method proposed in the present paper.

Melting entropy and enthalpy of metallic nanoparticles

2008 ◽  
Vol 62 (24) ◽  
pp. 3954-3956 ◽  
Author(s):  
M. Attarian Shandiz ◽  
A. Safaei
Keyword(s):  
Metallic Nanoparticles ◽  
Melting Entropy

scholarly journals Effect of Size and Shape on the Vibrational and Thermodynamic Properties of Nanomaterials

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
R. Kumar ◽  
G. Sharma ◽  
M. Kumar
Keyword(s):  
Experimental Data ◽  
Thermodynamic Properties ◽  
Size And Shape ◽  
Shape Dependence ◽  
Simple Theoretical Model ◽  
Model Predictions ◽  
Different Shapes ◽  
Debye Frequency ◽  
Good Agreement ◽  
Melting Entropy

A simple theoretical model is developed to study the size and shape dependence of vibrational and thermodynamic properties of nanomaterials. To show the real connection with the nanomaterials we have studied Debye temperature, Debye frequency, melting entropy, and enthalpy in different shapes, namely, spherical, nanowire, and nanofilm of -Fe, Sn, Ag, and In. The results obtained are compared with the experimental data. A good agreement between the model predictions and the experimental data supports the theory developed in the present paper.

Modelling for the Prediction of Melting Temperature for Metallic Nanoparticles

2020 ◽  
Vol 12 (1) ◽  
pp. 27-30
Author(s):  
Sachin ◽  
Brijesh K. Pandey ◽  
Ratan Lal Jaiswal
Keyword(s):  
Physical Properties ◽  
Melting Temperature ◽  
Metallic Nanoparticles ◽  
Marked Change ◽  
Simulated Data ◽  
Packing Fraction ◽  
Sharp Change ◽  
Fundamental Relation ◽  
Face Centered Cubic ◽  
Shape And Size

At nano level, materials show very interesting physical properties with the variation of shape and size. The prediction of this behaviour has been a burning issue in the recent years in the scientific community as well. Even the physical properties of these materials are poorly investigated experimentally. To explain the sharp change in the properties of metals, as reported by some investigators, at their nanolevel, different models have been proposed. It is observed that in their theoretical prediction, they have not considered the exact arrangement of atoms in the lattice. In our attempt to understand the behaviour of the nanomaterials, we have studied the melting temperature of some nanosolids having face centered cubic lattice such as Aluminium (Al), Copper (Cu), Paladium (Pd), Platinum (Pt) and Gold (Au), considering different shapes with their sizes ranging from 30 nm to more smaller dimensions. For modelling analysis, we have considered the very basic and fundamental relation of cohesive energy with melting temperature along with modification with two realistic physical quantities-packing fraction and particle shape factor simultaneously to account the arrangements of atoms within the nanoparticle and on the surface as well. Our study shows that there is a very marked change in the melting temperature of the metallic nanosolids below 20 nm. Although in the earlier reported works, it has been claimed that this variation occurs at somewhat higher values. In this variation, the tetrahedral structure exhibits maximum variation of melting temperature while spherical one corresponds to the minimum change. In case of gold, our simulated data has been compared with available experimental values which is found in good agreement with it. This agreement between experimental and computed data validates our proposed model for the prediction of melting temperature of nanoparticles at varying dimensions viz, shape and size. Thus our proposed modification in the existing model is more appropriate in the prediction of melting point of nanoparticles with its varying shape and size.

scholarly journals Modeling for the study of thermophysical properties of metallic nanoparticles

2021 ◽  
Vol 3 (4) ◽  
Author(s):  
Ratan Lal Jaiswal ◽  
Brijesh Kumar Pandey
Keyword(s):  
Thermodynamic Properties ◽  
Specific Heat ◽  
Thermophysical Properties ◽  
Cohesive Energy ◽  
Metallic Nanoparticles ◽  
Shape Effect ◽  
Great Effort ◽  
Dangling Bond ◽  
Experimental Findings ◽  
Melting Entropy

AbstractSuccessful description and explanation of thermophysical properties at the nano level is a task of great challenge even yet today. Although great effort has been made by pioneer workers and scientists in this field but still the exact model for the prediction and explanation of these properties is lagging. In the current work, we have proposed a new model to calculate the thermophysical properties like specific heat, melting enthalpy, and melting entropy of nanomaterials, which are calculated with the help of a cohesive energy model including shape effect in addition to structure of materials at the nano level. The relaxation factor due to the dangling bond at the surface of nanoparticles is taken under consideration. The obtained results using this model is fully consistent with the available experimental findings for the above said thermophysical properties for silver (Ag), copper (Cu), Palladium (Pd), Aluminium (Al), and Indium (In). This encouraging idea has also been used to predict the nature of variation of above mentioned important thermodynamic properties of other materials at their nano level.

Representation, abstraction, and simple-minded sophisticates

2020 ◽  
Vol 43 ◽  
Author(s):  
Peter Dayan
Keyword(s):  
Decision Theory ◽  
Predictive Coding ◽  
Bayesian Decision Theory ◽  
Bayesian Decision ◽  
Model Based ◽  
Model Free

Abstract Bayesian decision theory provides a simple formal elucidation of some of the ways that representation and representational abstraction are involved with, and exploit, both prediction and its rather distant cousin, predictive coding. Both model-free and model-based methods are involved.

The Alteration of the Pore Spaces in Sandstones

1973 ◽  
Vol 31 ◽  
pp. 210-211
Author(s):  
R. E. Ferrell ◽  
G. G. Paulson
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
The Other ◽  
Coarse Grained ◽  
Depositional Fabric ◽  
Soluble Components ◽  
Scanning Electron ◽  
Shape And Size

The pore spaces in sandstones are the result of the original depositional fabric and the degree of post-depositional alteration that the rock has experienced. The largest pore volumes are present in coarse-grained, well-sorted materials with high sphericity. The chief mechanisms which alter the shape and size of the pores are precipitation of cementing agents and the dissolution of soluble components. Each process may operate alone or in combination with the other, or there may be several generations of cementation and solution.The scanning electron microscope has ‘been used in this study to reveal the morphology of the pore spaces in a variety of moderate porosity, orthoquartzites.

Sign in / Sign up

Export Citation Format

Share Document